title: Fluctuation/correlation effects in symmetric diblock copolymers: on the order-disorder transition.
abstract: Using fast off-lattice Monte Carlo simulations with experimentally accessible fluctuations, we reported the first systematic study unambiguously quantifying the shift of the order-disorder transition (ODT) χ* of symmetric diblock copolymers from the mean-field prediction χ(MF)*. Our simulations are performed in a canonical ensemble with variable box lengths to eliminate the restriction of periodic boundary conditions on the lamellar period, and give the most accurate data of χ* and bulk lamellar period reported to date. Exactly the same model system (Hamiltonian) is used in both our simulations and mean-field theory; the ODT shift is therefore due to the fluctuations/correlations neglected by the latter. While χ*/χ(MF)*-1∝N(-k) is found with N denoting the invariant degree of polymerization, k decreases around the N-value corresponding to the face-centered cubic close packing of polymer segments as hard spheres, indicating the short-range correlation effects.
authors.affiliation: Department of Chemical and Biological Engineering, Colorado State University, Fort Collins, Colorado 80523-1370, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zong
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang